Most people still are running 32-bit operating systems, which max out at just over 3 gigs of system memory. (If you don't understand why, there is an excellent explanation at Corsair's Gaming Performance Analysis page, which I have given a link to in the "Testing - Loading Times" section of this review.) But face it, 2 gigabytes of system memory just isn't enough for today's games. There have been tests emerging lately proving what I have known for a few months, the latest games perform better with 4 gigs of system memory. When I first bought Crysis, I was running 2 gigs, and it played ok, but when I replaced my system memory with 4 gigs, it was like my system was able to open up and breathe, and made the game much more playable.

I've seen a few articles recently about testing between 2GB and 4GB kits. Corsair has done their own testing. I've done my own personal testing too. All the results were similar. In artificial benchmarks, the 4GB kit gets slightly better marks. In gaming, the 4 gig kit nearly always got a few more FPS. But the real difference isn't in benchmark scores.it is in how fast the benchmark software loads. Corsair and my results were nearly identical. games like Crysis load much faster with 4 gigs of system memory. Maps load as much as twice as fast. Another biggie is switching from large application to large application, such as leaving a game to go to Photoshop to paste and edit a screenshot.

Even putting a 4GB kit on a 32-bit system, though the system will only use 3-3.2 gigs of the memory, depending mainly on how much memory your video card has, makes a noticeable difference.

DDR3 prices are steadily falling as the technology is improving, so 4 gig DDR3 kits are beginning to emerge. This is my first 4 gig DDR3 kit, and I have been anxiously awaiting it, to get some 4 gig goodness from my DDR3 test rig.

The modules are verified at DDR3-1600, 9-9-9-24, running at 1.8v. Yes, there are 2GB DDR3-1600 modules running lower latencies out there, Corsair has them too, for about twice the price of these. If you look at them they all run a 1.9v Vdimm. At 1.8v, these will surely run cooler, and will likely have some headroom for additional performance.

A close look at the DHX heat spreaders shows that they aren't as simple as they appear. There are actually two pairs of heatsinks on each module. One pair is physically mounted to the outside of the memory chips, cooling the IC's themselves. A second pair is mounted directly to the PCB's. If you haven't thought about it, the circuit board itself serves as a heatsink to whatever is mounted on it, and it can get tremendously hot. If you don't believe me, feel the back of your video card while gaming. System memory modules have memory chips on both sides of the PCB, and while the traditional heat spreader cools the front of the memory chips, it is very hard for the rear of the chips to get any real cooling at all, and heat builds up on the PCB.

The hot PCB can cause instability, but Corsair has solved that problem by mounting a pair of additional heatsinks on the PCB itself. This cools both side of the hot memory chips, creating an environment more conducive to stability.

If you notice, the heatsinks themselves are fairly thick. You'd think that the memory modules would be pretty heavy, but the heatsinks are made of a very light alloy, and the modules are surprisingly light.

The TW3X4G1600C9DHXNV is EPP 2.0 certified by nVidia. From Corsair:

The TW3X2G1600C9DHXNV is a 4096MByte kit of DDR3 SDRAM DIMMs based upon Corsair's high performance XMS3 DHX family of memory which is certified as SLI-Ready Memory. NVIDIAEPP2.0 SLI-Ready system memory certification ensures compatibility and system stability with the rest of the SLI ecosystem components including NVIDIA nForce SLI motherboards, NVIDIAGeForce GPUs, and SLI-Ready power supplies. Specifically, when these memory modules are paired with NVIDIA nForce SLI-based motherboards, advanced performance memory settings are enabled.

There is another model of this memory, it has the same specs, but without nVidia EPP.